Features of the Energy Spectrum of Cosmic Rays above 2.5 x 10**18 eV Using the Pierre Auger Observatory

THE PIERRE AUGER COLLABORATION; DIEGO G. MELO

PHYSICAL REVIEW LETTERS

AMER PHYSICAL SOC

Lugar: New York; Año: 2020

0031-9007

We report a measurement of the energy spectrum of cosmic rays above 2.5 x 10**18 eV based on 215030 events. New results are presented: at about 1.3 x 10**19 eV, the spectral index changes from 2.51 +/- 0.03 (stat) +/- 0.05 (syst) to 3.05 +/- 0.05 (stat) +/- 0.10 (syst), evolving to 5.1 +/- 0.3 (stat) +/- 0.1 (syst)  beyond 5 x 10**19 eV, while no significant dependence of spectral features on the declination is seen in the accessible range. These features of the spectrum can be reproduced in models with energy-dependent mass composition. The energy density in cosmic rays above 5 x 10**18 eV is [5.66 +/- 0.03 (stat) +/- 1.40 (syst)] x 10**53 erg Mpc**(-3)